The present invention relates to power clamps used in industry, and in particular, to a sensor for sensing the position of a clamp arm of a power clamp.
Power clamps provide a pneumatic and hydraulic cylinder that drives a rotating clamp arm. Depending on the application, the clamp arm may rotate in an arc ranging from 18 to 118 degrees between a clamped and unclamped position.
When power clamps are used in automated processes, it is desirable to develop an electrical signal indicating the position of the clamp so that the clamping process may be monitored and verified. Traditionally this has been done by detecting a position of the piston in the cylinder of the power clamp. Monitoring the piston, however, is less than ideal, in part, because it only indirectly indicates the position of the clamp arm and cannot detect possible failure of the clamp arm rotating mechanism.
U.S. Pat. No. 5,694,042 describes a sensor for a power clamp that senses the position of the clamp arm directly by attaching two sensing disks directly to a free end of the axle of the clamp arm opposite the clamp arm. The sensor described is relatively bulky and thus may not be suitable for applications requiring tight clearances. Further, the sensor requires special modification of that axle through the drilling of holes into the axle by which to mount the sensing disk.